Why doesn't my mac recognise my hardrive or SD cards?

I got a new Macbook Air last month. Since then I have been having so many problems with it- mostly because if you plug in anything into the SD card slot or the USB drives, it won't recognise them. I has a mac before, as well as dell laptop, so I am aware of the problems when formatting disks across, but even when I plugged a new passport external hard drive in, the computer couldn't find it. Similarly, it cannot find any SD cards when i have tried to use the SD card slot.

Whats going on with this? I'm a photographer by living, so I need constant access to both these. Does this newest model have some new process for transfering files from external hard drive etc?